Technical Field
The present invention relates to a cooling device for an internal combustion engine, and a cooling method for an internal combustion engine, in particular, relates to a technique for preventing a heat exchanger from being damaged due to thermal deformation when cooling water having increased temperature is supplied to the heat exchanger.
Related Art
An internal combustion engine mounted on a vehicle is provided with a cooling-water flow path, which allows cooling water to pass therethrough. In the case where temperatures of the internal combustion engine are desired to be reduced, the cooling water is caused to flow within the heat exchanger (for example, a radiator) to reduce temperatures of the cooling water, and then, the cooling water, having reduced temperature, is caused to pass through the cooling-water flow path of the internal combustion engine. The cooling water passing through the cooling-water flow path in the heat exchanger exchanges heat with the internal combustion engine, whereby temperatures of the internal combustion engine are controlled so as to be a desired temperature.
If the cooling water having increased temperature suddenly enters the heat exchanger at normal temperatures at the start of the internal combustion engine, a temperature difference takes place before and after the entrance of the cooling water, which causes the heat exchanger to suffer from thermal impact (also referred to as “thermal shock”). This thermal impact possibly leads to occurrence of thermal deformation in the heat exchanger. With the aim of alleviating the thermal deformation, Patent Literature 1 discloses a technique of detecting an inlet temperature and an outlet temperature of the cooling water passing through the heat exchanger, and controlling the volume of flow of the cooling water supplied to the heat exchanger so that the difference in temperatures does not increase.